The present invention relates to a switching control device for transmitting calls received by a cellular phone to a fixed network telephone. Such a device enables people to receive calls transmitted to a cellular phone via a fixed network telephone particularly equipped with a plurality of extension lines by conversion operations. The present invention operates with a cellular phone/fixed network telephone switching device in cooperation with an on/off device. When a cellular phone receives an incoming call, the switching device will first detect the main telephone set and its extension lines of their individual status of use; and the on/off device is selectively actuated of its on and off states and vibration ring operation according to the detection. Thereby a user can pick up a nearest extension line without rushing back to a main telephone set when an incoming call is transmitted to a cellular phone.
Cellular phones have been widely and popularly used by people in modern cities all over the world because they make instant communication possible at any places and any time, facilitating people in everyday life. However, the frequent use of cellular phones do cause bad effect on people""s health, especially microwaves can cause people""s brains damaged without notice. So, the use of cellular phones brings crisis to people""s health. In such a situation, people aware of the danger of using cellular phones try to reduce the frequency of use of cellular phones indoors, they will use cellular phones only outdoors. But many important personal contacts are generally made via cellular phones at homes or in offices, and turning off cellular phones can cause personal communication inconvenient. In that case, people are forced to make use of cellular phones all the time even inside houses with common telephones. To make cellular phones adapted to be operable on an indoor fixed-network telephone, such as at homes and in offices, has been a major concern by people. Such a fixed-network telephone can transform cellular phone calls into communication via the fixed-network telephone.
The conventional device for effecting such a communication transformation is illustrated in FIG. 1. It mainly includes a switching device 11 to which a cellular phone T is to be in inserting connection. Then the switching device 11 is coupled to a fixed network telephone 12 so that incoming calls of the cellular phone T can be transmitted via transformation operations of the switching device 11 to the fixed network telephone 12. When such a switching device 11 is applied to a fixed network telephone with extension lines, there are several problems found in practical use. Referring first to FIG. 2 which shows the wire arrangement of a fixed network telephone with a number of extension lines. The fixed network wiring 3 mainly comprises a main line 30 branched into a main telephone set 32 and several extension lines 33, 34, 35; and only the main telephone set 32 is equipped with a cellular phone/fixed network telephone switching device 31. Once an incoming call is transmitted to the cellular phone T, a person can only receive the call by way of the main telephone set 32. The remaining extension lines will not receive any vibration ring signals at all. Thus, the extension lines become useless in such a situation. This will force a person to rush to the place where the main telephone set 32 is located. Such a problem makes the prior switching device a major disadvantage in use.
Therefore, the primary object of the present invention is to provide a switching control device for transmitting a cellular phone call to a fixed-network telephone particularly equipped with extension lines in such a manner that people can get a transformed call at the nearest extension line without rushing back and forth in an office or at home.